CN101308630A - LCD device - Google Patents

See also Fig. 1, it is a kind of electrical block diagram of prior art LCD.This

LCD

100 comprises a

power circuit

11, a signal processor (Scaler) 15, a

liquid crystal panel

16, an

inverter

17 and a

module

18 backlight.This

power circuit

11 changes extraneous alternating voltage into DC voltage and transmits to this

signal processor

15,

liquid crystal panel

16 and

inverter

17 respectively, this

signal processor

15 receives the vision signal of extraneous input and sends vision signal and control signal to this

liquid crystal panel

16, this

signal processor

15 transmits control signal to this

power circuit

11 and inverter 17 simultaneously, and this

inverter

17 provides its operate as normal required High AC voltage to this

module

18 backlight.

The proper operation method of closing this

LCD

100 is the mechanical switchs (figure does not show) that touch by on its shell (figure does not show).When these

LCD

100 operate as normal, touch by this mechanical switch once, this mechanical switch sends control signal corresponding to this

signal processor

15, this

signal processor

15 is at first controlled this

inverter

17 and is stopped to provide voltage to this

module

18 backlight, and promptly this

module

18 backlight is at first closed.This

signal processor

15 stops to send vision signal to this

liquid crystal panel

16 then.These

signal processor

15 last these

power circuits

11 of control stop to 16 power supplies of this liquid crystal panel.This shutdown mode is called direct current shutdown (DC Off) again.

When the external world stopped to 100 power supplies of this LCD suddenly, each element almost was to cut off the power supply simultaneously, and as shown in Figure 2, this shutdown mode is called ac dump (ACOff).Ac dump is not only bigger to each element injury, and can produce the shutdown noise, and promptly this

LCD

100 shows error picture, thereby has reduced display quality.

See also Fig. 3, it is the electrical block diagram of LCD of the present invention.This

LCD

200 comprises a

power circuit

21, a

signal processor

25, a

liquid crystal panel

26, an

inverter

27, one

module

28 backlight and an AC shutdown control circuit 30.This

power circuit

21 changes extraneous alternating voltage into DC voltage and transmits to this

signal processor

25,

liquid crystal panel

26 and

inverter

27 respectively, this

signal processor

25 receives the vision signal of extraneous input and sends vision signal and control signal to this

liquid crystal panel

26, this

signal processor

25 transmits control signal to this

power circuit

21 and inverter 27 simultaneously, and this

inverter

27 provides its operate as normal required High AC voltage to this

module

28 backlight.This AC

shutdown control circuit

30 is serially connected between this

power circuit

21 and this

signal processor

25.

See also Fig. 4, it is the circuit structure diagram of AC

shutdown control circuit

30 shown in Figure 3.This AC

shutdown control circuit

30 comprises an

input end

31, a

sample circuit

32, an on-off

circuit

37, a

signal input end

38 and an output terminal 39.This

input end

31 is electrically connected with this

power circuit

21, and this

signal input end

38 is electrically connected with a direct current power supply (figure does not show), and this

output terminal

39 is electrically connected with this signal processor 25.The input signal of 32 pairs of

input ends

31 of this sample circuit is handled and is sent control signal corresponding to this on-off

circuit

37, this on-off

circuit

37 corresponding conductings or close this

signal input end

38 and this

output terminal

39.

See also Fig. 5, it is the circuit structure diagram of a kind of better embodiment of AC shutdown control circuit shown in Figure 4.This

sample circuit

32 comprises one

first resistance

33, one

second resistance

34, an

electric capacity

35 and a

diode

36, and this on-off

circuit

37 comprises a

bipolar transistor

40, and this

bipolar transistor

40 is positive-negative-positive bipolar transistors.The positive pole of this

diode

36 is connected with this

input end

31 by this

first resistance

33, the positive pole of this

diode

36 is simultaneously by these second resistance, 34 ground connection, the negative pole of this

diode

36 is by these

electric capacity

35 ground connection, and the negative pole of this

diode

36 is electrically connected with the base stage of this

bipolar transistor

40 simultaneously.The emitter-base bandgap grading of this

bipolar transistor

40 is connected with this

signal input end

38, and its collection utmost point is connected with this

output terminal

39.

When these

LCD

200 operate as normal, what this

input end

31 received is through the filtered alternating voltage of electromagnetic compatibility in the AC power, this alternating voltage is through the bleeder circuit dividing potential drop of these first,

second resistance

33,34 formations and export a direct current voltage to the base stage of this

bipolar transistor

40 behind the current rectifying and wave filtering circuit rectifying and wave-filtering of this

diode

36 and this

electric capacity

35 formations, this DC voltage is higher than the voltage of these

bipolar transistor

40 emitter-base bandgap gradings, and this

bipolar transistor

40 is in closed condition.

When these

LCD

200 sudden power, the alternating voltage that this

input end

31 receives reduces rapidly, and the DC voltage of these

bipolar transistor

40 base stages is also corresponding to be reduced, and this

bipolar transistor

40 is in opening at this moment.This

signal input end

38 and these

output terminal

39 conductings, the voltage of this direct supply (promptly closing machine control signal) inputs to this

signal processor

25 by this

signal input end

38, this

bipolar transistor

40 and this

output terminal

39, this

signal processor

25 is at first controlled this

inverter

27 and is stopped to provide voltage to this

module

28 backlight, promptly this

module

28 backlight is at first closed, as shown in Figure 6.This

signal processor

25 stops to send vision signal to this

liquid crystal panel

26 then, and this action has T apart from last action ₁Time.These

signal processor

25 last these

power circuits

21 of control stop to 26 power supplies of this liquid crystal panel, and this action has T apart from last action ₂Time.Be about to the ac dump state and switch to the direct current off-mode.

Compared with prior art,

LCD

200 of the present invention adopts this AC

shutdown control circuit

30 that the ac dump state is switched to the direct current off-mode, thereby has eliminated the shutdown noise.

In this AC

shutdown control circuit

30, this

bipolar transistor

40 also can be NP N type bipolar transistor.This

bipolar transistor

40 can also change field-effect transistor into, and the grid of this field-effect transistor is electrically connected with this

sample circuit

32, and its drain electrode is connected with this

signal input end

38, and its source electrode is connected with this

output terminal

39.

LCD

200 of the present invention also can be in this

power circuit

21 or this

signal processor

25 an integrated AC shutdown control circuit, its principle of work and aforementioned AC

shutdown control circuit

30 are basic identical.

1. LCD, it comprises a power circuit and a signal processor, it is characterized in that: this LCD also comprises an AC shutdown control circuit, this AC shutdown control circuit is serially connected between this power circuit and this signal processor, and this AC shutdown control circuit detects the duty of this power circuit and transmits control signal corresponding to this signal processor.

2. LCD as claimed in claim 1, it is characterized in that: this AC shutdown control circuit comprises an input end, a sample circuit, an on-off circuit, a signal input end and an output terminal, this input end is electrically connected with this power circuit, this output terminal is electrically connected with this signal processor, this sample circuit is handled the input signal of input end and is sent control signal corresponding to this on-off circuit, the corresponding conducting of this on-off circuit or close this signal input end and this output terminal.

3. LCD as claimed in claim 2 is characterized in that: this LCD also comprises a direct current power supply, and this direct supply is electrically connected with this signal input end.

4. LCD as claimed in claim 2 is characterized in that: this sample circuit comprises a bleeder circuit and a current rectifying and wave filtering circuit, and the alternating voltage of this input end becomes DC voltage behind this bleeder circuit and this current rectifying and wave filtering circuit.

5. LCD as claimed in claim 4 is characterized in that: this bleeder circuit comprises one first resistance and one second resistance, and this first, second resistance string is associated between this input end and the ground.

6. LCD as claimed in claim 5, it is characterized in that: this current rectifying and wave filtering circuit comprises a diode and an electric capacity, the positive pole of this diode is connected with this input end by this first resistance, the positive pole of this diode is simultaneously by this second resistance eutral grounding, the negative pole of this diode is by this capacity earth, and the negative pole of this diode is electrically connected with this on-off circuit simultaneously.

7. as claim 2 or 6 described LCD, it is characterized in that: this on-off circuit comprises a bipolar transistor, the base stage of this bipolar transistor is electrically connected with this sample circuit, and its emitter-base bandgap grading is connected with this signal input end, and its collection utmost point is connected with this output terminal.

8. as claim 2 or 6 described LCD, it is characterized in that: this on-off circuit comprises a field-effect transistor, the grid of this field-effect transistor is electrically connected with this sample circuit, and its drain electrode is connected with this signal input end, and its source electrode is connected with this output terminal.

9. LCD, it comprises a power circuit and a signal processor, it is characterized in that: this LCD also comprises an AC shutdown control circuit, when this power circuit sudden power, this AC shutdown control circuit is sent control signal corresponding to this signal processor, and this LCD of the corresponding control of this signal processor enters the direct current off-mode.

10. LCD as claimed in claim 9, it is characterized in that: this AC shutdown control circuit comprises an input end, a sample circuit, an on-off circuit, a signal input end and an output terminal, this input end is electrically connected with this power circuit, this output terminal is electrically connected with this signal processor, this sample circuit is handled the input signal of input end and is sent control signal corresponding to this on-off circuit, the corresponding conducting of this on-off circuit or close this signal input end and this output terminal.